This is a delicious cookie crust pastry -- rich with eggs, butter and sour cream and is filled with a generous layer of apples. Use firm cooking apples such as Granny Smith, McIntoch, Rome Beauty or Braeburns or a combination of cooking apples. I used 3 Granny Smith, 3 Cortland and 3 large Crispins for my Korzh. This cake is best served the next day at room temperature. Or give it at least 5 hours before cutting after it has cooled. The dough takes a bit of effort to knead so keep kneading until it is smooth. This dough also makes delicious cookies. NOTE: Do not mix the apples with the sugar until the very last minute before you place them in the dough lined pan because if you do this ahead of time the apples will release their juices and it will be too watery.

FOR THE DOUGH: Stir together the flour, baking powder, salt, and sugar in a large bowl. Add the butter and work it into the flour with your fingertips to make a coarse flaky mixture, then rub the mixture rapidly between your palms to make fine crumbs. In a small bowl, whisk the egg yolks and sour cream together until smooth. Add to the dry ingredients and work everything together with your hands to make a firm, smooth, not sticky dough.

Divide the dough into 2 pieces, making one piece slightly larger. Pat each portion into a 1-inch thick rectangle. You can work with the dough right away or wrap it tightly in plastic wrap and refrigerate. The dough can be made up to a day ahead and refrigerated; bring to room temperature before rolling.

Adjust an oven rack to the center position and preheat the oven to 375º F. Butter a 13 x 9 x 2-inch baking pan preferably nonstick. NOTE: Do not use cooking spray--you want the dough to stick to the butter, and it will not stick to the cooking spray.

From the large dough portion, using about 1/3 of it, pinch of small pieces of dough and press them onto the sides of the pan, going up halfway. The thickness of the dough should be slightly more than 1/8 inch thick. Don't be concerned about uneven edges, but try not to make the corners too thick. Roll the remaining portion of this piece of dough on a lightly floured surface to fit the bottom of the pan. If the dough tears, just pinch it together. Carefully lift the dough onto the pan and press the dough with your fingertips to join with the sides. The bottom crust will be slightly thicker than the sides.

Lightly dust your work surface with flour and coat both sides of the smaller piece of dough with flour. If the dough feels very firm, tap it gently with a rolling pin to soften it a bit. Roll the dough to a rectangle the size of the top of the baking pan. Use a ruler to make sure. The dough will be be about 1/4 inch thick. Check frequently during rolling to make sure the dough isn't sticking to the work surface; if it is, loosen it with a pastry scraper. If it cracks in several place, particularly along its sides; simply pinch the dough together, squaring off any rough edges.FOR THE FILLING: Quarter, core and peel the apples. Cut crosswise into thin slices and then cut the slices into short matchstick shapes. Put the apples into a large bowl. Stir together the sugar, cinnamon, and salt and toss with the apples to combine. Transfer the apples to the dough-lined pan, distribute them evenly, and pat them gently into place. Carefully place the top crust onto the apples. Pinch the edges of the top and bottom crust with your fingertips to seal the two together. Prick the top crust at 1-inch intervals with a fork.

Bake for 45 to 55 minutes, until the pastry is a rich golden brown color, the apples smell fragrant, and a paring knife inserted into the apples passes through them with no resistance. Set the pan on a wire rack to cool for 20 to 30 minutes.

Run the tip of a small sharp knife all around the pastry to release it. Cover it with a long wire rack the same size as the pan, grasp the pan and rack together, and invert the two. Slowly lift off the pan. Cover the bottom of the Korzh with another wire rack and invert again so that it is right side up. Cool completely on the wire rack, then slide the Korzh onto a platter or wooden cutting board, cover loosely with plastic wrap, and let stand overnight at room temperature.

To serve, dust the top of the korzh with confectioners' (Icing/Powdered) sugar and cut into portions with a sharp serrated knife. Makes 16 to 18 servings.

Store the leftover in the refrigerator, but bring to room temperature before serving. Dust again with confectioners' sugar if necessary.